An N-methyl-D-aspartate (NMDA) receptor (hereinafter referred to as “NMDAR”) is one type of glutamate receptor.
The NMDAR has been considered to be a receptor that is involved in memory and learning. Therefore, the NMDAR has been one of the targets of Alzheimer-type dementia therapeutic agents.
D-serine is present in the mammalian brain, and is involved in control of the functions of the NMDAR as an endogenous coagonist.
D-serine is synthesized from L-serine by serine racemase (SR).
It has been known that an SR knock-out (KO) mouse shows a reduction in NMDA-induced neurodegeneration (see Non-patent Document 1), and a reduction in PTZ-induced epileptic seizure, for example.
Therefore, SR has been considered to be a new drug target for pathological conditions due to excessive nervous excitement. A dipeptide and the like have been known as an SR inhibitor (see Non-patent Document 2).